This project has explored approaches, methods, and concepts for assessing the clinical performance of laboratory tests. Focus has been on basic discrimination accuracy as reflected in clinical sensitivity and specificity and as represented by receiver operating characteristic (ROC) curves. As part of this effort the Subcommittee on Clinical Evaluation of Tests was formed, with Mark Zweig as chairholder, by the National Committee for Clinical Laboratory Standards. The objective was to develop guidelines for assessing the clinical performance of laboratory tests. A proposed guideline entitled "Assessment of Clinical Sensitivity and Specificity of Laboratory Tests" has been published, and is now undergoing revision through the consensus process.